This invention relates to bicycle and motorcycle suspensions, and in particular to such suspensions which are connected from only one side rather than both sides as is more conventional.
Bicycles and motorcycles were originally built with rigid frames. As the horsepower, weight and speed of motorcycles increased, and they began to be used off road, both front and rear wheel suspensions were developed and have now reached a very high degree of sophistication. Many different arrangements have been used for springing and damping rear suspensions, including complex linkages. The majority of rear suspensions on two wheeled vehicles however, still use a fork-type rear swingarm as the main rear suspension structural member, no matter what type of springing, damping and linkages are used. The "fork" type swingarm has a member on each side of the rear wheel, these members are fixed together at the front pivot area, and are joined at the rear by a rear axle which clamps the wheel between the members. Changing the wheel, tire, brake, rotor, or wheel bearings requires removal of the rear axle from both members of the fork.
A few alternative designs, such as Buell, U.S. Pat. No. 4,058,181, invented by the present inventor, have used a pair of forked members one above the other, for a total of four essentially longitudinal members. Any removal of any of the wheel parts on such a system, though, still requires removal of the axle.
Automobiles of course employ cantilevered stub-axles which allow wheels, brakes, etc. to be removed easily. A few two-wheeled vehicles have used a single-sided swingarm, such as that shown in Seino, et al., U.S. Pat. No. 4,809,802. Generally such a single-sided swingarm has taken the form of a large section tubular member connected along one side of the wheel, the tubular member being attached at its front to the frame with a bearing set mounted on a single axis. Because the side loads on the wheel are transferred through this tubular member in torsion only, the member is large and heavy, yet provides only mediocre lateral and torsional rigidity. Since lateral and torsional rigidity are of paramount importance in two wheel vehicle chassis design, these earlier designs have met with little success.
This invention relates to improvements to the apparatus described above and to solutions to some of the problems raised or not solved thereby.